1. Technical Field
The present invention relates generally to optical lenses, and more particularly to a zoom lens.
2. Description of Related Art
With the help of recent advances in imaging technology, the size and weight of zoom lenses used in optical image devices, especially in portable ones such as cameras or camcorders, are greatly reduced. And while optical image devices are being made miniature and lightweight, the manufacturers would always try to improve optical performance thereof to provide higher resolution and better contrast. Obviously, miniature and high optical performance are two key design considerations for zoom lenses nowadays.
To achieve the above purpose of making miniature devices, some optical image devices are designed to have a collapsible zoom lens which can be collapsed into an outer case. However, the lenses in mainstream usually include multiple lens groups composed of many (even more than 10) lens elements in order to satisfy the requirement of high optical performance, and therefore such lenses are still too thick even after being collapsed. There is still room for improvement.